My wife's mother passed away at the end of October, so we had to arrange flights for us back to the UK from the USA at short notice.

On the evening of Friday November 2nd I went on the British Airways website, clicked on "Flight" and found something suitable (going out Club World and back World Traveller Plus).

Since I have an eVoucher I clicked on "Use promotion code or eVoucher". I noticed on the next screen that my booking had changed to going out and back World Traveller Plus, which I did not want.

Assuming that the same thing would happen if I tried again, and wanting to get the booking done as prices go up as the travel date approaches, I decided to book using my credit card and contact Customer Service to have them retroactively apply the eVoucher.

I redid the booking and proceeded without clicking on "Use promotion code or eVoucher" and, during the process, was presented with a screen that said "Add car rental to your booking". Since I needed to rent a car, and this seemed the easy option, I added a car, and paid for flights and car using my credit card.

I then e-mailed Customer Service, explaining that the BA website had not let me use the eVoucher to part-pay for my flights only booking and asking them to retroactively apply it. Its being Friday evening, they were unable to reply before Monday. Their reply was that, since when I re-booked I had added a car, the eVoucher was no longer useable.

I quite understand that, had I booked a third-party car costing $thousands and flights from BA costing $hundreds then BA would not want me using a BA voucher against the total cost, but since 97% of my total cost was for BA flights it is manifestly unjust to disallow my voucher because 3% of the total is going to a third party.

Had the British Airways website worked as it was supposed to, my flights-only booking would have been processed using my voucher as part-payment. It was only because the website did not work correctly that I had to re-book and was suckered by their marketing into adding a car AFTER booking my flights.

Incidentally, I went on BA.com today to try to make a booking similar to that I attempted on November 2nd and I had the exact same result - my outgoing flight was changed from Club World to World Traveller Plus when I clicked on "Use promotion code or eVoucher".

I also tried to book a one-way Economy flight from Oporto to Gatwick yet, when I clicked on "Use promotion code or eVoucher", I was taken to a page that only accepted credit card information and provided no way to enter any eVoucher information.

So, despite my alerting British Airways to the problem a month ago, there is still no way that flights booked through the British Airways website can be paid for using an eVoucher yet the information on that website clearly states that "You can use an eVoucher in full or part payment of flight bookings on ba.com".